Absorbent structures and cores with efficient immobilization of absorbent material

ABSTRACT

An absorbent structure comprising a planar substrate, an auxiliary glue applied on the substrate, an absorbent material comprising from 80% to 100% by weight of superabsorbent particles deposited on the substrate on an absorbent material deposition area comprising a pattern of absorbent material land areas separated by absorbent material-free junction areas, wherein the deposition area can be notionally divided in eight deposition zones of equal length along the longitudinal direction. A fibrous thermoplastic adhesive layer immobilizes at least some of the absorbent material. The absorbent material is profiled along the longitudinal direction so that at least one of the eight deposition zones is a zone of lower absorbent material amount and the auxiliary glue is absent, or present at a level of at least 50% by weight lower than the average amount of auxiliary glue in at least one of these zones of lower absorbent material amount.

FIELD OF THE INVENTION

The invention relates to absorbent structures and absorbent cores thatcan be used in personal hygiene articles such as, but not limited to,baby diapers, training pants, feminine pads or adult incontinenceproducts.

BACKGROUND OF THE INVENTION

Absorbent articles for personal hygiene, such as baby diapers, trainingpants for toddlers, feminine pads and adult incontinence undergarments,are designed to absorb and contain body exudates, in particular largequantity of urine. These absorbent articles comprise several layersproviding different functions, for example a topsheet, a backsheet andan absorbent core positioned between the topsheet and backsheet, amongother layers. The key functions of the absorbent core are to absorb andretain the exudates for a prolonged period of time, for exampleovernight for a diaper, to minimize re-wet to keep the wearer dry and toavoid soiling of clothes or bed sheets.

The majority of currently marketed absorbent articles comprise asabsorbent material a blend of comminuted wood pulp with superabsorbentpolymers (SAP) in particulate form, also called absorbent gellingmaterials (AGM), for example as disclosed in U.S. Pat. No. 5,151,092(Buell). The SAP provides most of the absorbent capacity while thecellulose fibers can serve to immobilize the SAP within the core.Absorbent cores consisting essentially of SAP without cellulose fibers(also airfelt-free cores) have been proposed for example inWO2004/071539 (Busam), WO2008/155699 (Hundorf), WO95/11652 (Tanzer) orWO2012/052172 (Van Malderen). Removing the cellulose fibers has theadvantage of providing thinner cores, but creates new challenges interms of immobilization of the SAP in dry and wet state. This problemhas been addressed in Busam and Hundorf by spraying a fiberized hot-meltthermoplastic material on a discontinuous SAP layer. These documentsalso consider using an auxiliary glue to improve the adhesion of thethermoplastic material to the substrate layer. More recently,WO2010/027719 (Hundorf) disclosed an improved process for making suchcellulose free absorbent core using a plurality of cross-bars.

There is a continuous need for providing improved absorbent cores thatbalance absorbency performance with material saving. The presentinvention provides an improvement to the previously proposed coreshaving little or no cellulose fibers. The absorbent structures and coresof the invention have a profiled absorbent material distribution toprovide higher amount of absorbent material where it is most needed,typically towards the crotch and to a lesser extent front of theabsorbent structure or core, while eliminating or at least substantiallyreducing the auxiliary glue in the zones having low amount of absorbentmaterial, typically towards the back of the absorbent structure and/ortowards the front of the structure. This combination of featuresprovides a reduction of adhesive usage while maintaining high absorbencyperformance and good dry and wet SAP immobilization properties.

SUMMARY OF THE INVENTION

The present invention is, in a first aspect, for an absorbent structureas indicated in the claims. The structure comprises a substantiallyplanar substrate extending in a transversal directions (x) and alongitudinal direction (y), an auxiliary glue applied directly over thesubstrate on an auxiliary glue application area, an absorbent materialdeposited on the substrate in a pattern comprising absorbent materialland areas separated by absorbent material-free junction areas, theperiphery of the pattern defining an absorbent material deposition area,and a fibrous thermoplastic adhesive layer which covers at least some ofthe land areas and the absorbent material-free junction areas to therebyimmobilize at least some of the absorbent material on the substrate. Theabsorbent material comprises from 80% to 100% by weight ofsuperabsorbent particles.

The absorbent material deposition area can be notionally divided ineight zones of equal length along the longitudinal direction of thestructure. The absorbent material is profiled along the longitudinaldirection of the structure so that at least one of the eight depositionzones is a zone of lower absorbent material amount, hereby defined ashaving an amount of absorbent material that is at least 20% by weightlower than the average amount of absorbent material in the eightdeposition zones (which together forms the absorbent material depositionarea). The auxiliary glue is absent, or present at a level of at least50% lower than the average amount of auxiliary glue in the eightdeposition zones, in at least one of these deposition zones of lowerabsorbent material amount.

In a second aspect, the absorbent structure can be combined with asecond substrate, which can also be part of a second absorbentstructure, to form an absorbent core, as indicated in the claims,wherein the first substrate and the second substrate together form acore wrap that encloses the absorbent material. The absorbent core maybe used in a wide range of absorbent articles in particular diapers andtraining pants. In a further aspect, the invention is for a method ofmaking the absorbent structure and the absorbent core of the invention.

The invention can be described in a simplified way as an absorbentstructure having a longitudinally profiled distribution ofsuperabsorbent particles which are immobilized by a fibrousthermoplastic adhesive layer and an auxiliary glue. The auxiliary glueis not applied or applied at a lower amount in the zones having arelatively low amount of superabsorbent material. The invention allowsto limit the usage of auxiliary glue to the zones where it is mostneeded, resulting in material cost saving and in some cases improvingliquid handling.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of an absorbent structure according to theinvention with the fibrous thermoplastic adhesive layer partiallyremoved;

FIG. 2 is an exploded perspective view of the structure of FIG. 1;

FIG. 3 is a cross-section view of the absorbent structure of FIG. 1along the longitudinal direction;

FIG. 4 is a longitudinal cross-section of an absorbent core comprisingthe absorbent structure of FIGS. 1-3 and a second substrate;

FIG. 5 is a longitudinal cross-section of an absorbent core comprisingthe absorbent structure of FIGS. 1-3 and a second absorbent structurecomprising a second auxiliary glue;

FIG. 6 is a longitudinal cross-section of an absorbent core comprisingthe absorbent structure of FIGS. 1-3 and a second absorbent structurethat does not comprise an auxiliary glue.

FIG. 7 shows a transversal cross-section of the core of FIG. 6;

FIGS. 8-11 schematically show alternative outlines for the auxiliaryglue application area and absorbent material deposition area.

FIG. 12 shows an exemplary absorbent article in the form of a diapercomprising an absorbent core of the invention;

FIG. 13 shows a schematic apparatus for making an absorbent structureand core of the invention.

It should be understood that cross-section views have been expanded inthe vertical direction to better show the arrangement of the differentlayers comprised by the structures and cores. The structures and coresthus appear much thicker in these Figures than in reality.

DETAILED DESCRIPTION OF THE INVENTION

Introduction

In a first aspect, the present invention is for an absorbent structure70 as exemplarily illustrated in FIG. 1-3. The absorbent structure maybe used to make an absorbent core 28 as exemplarily illustrated in FIG.4-7, which may be incorporated in an absorbent article as exemplarilyshown in FIG. 12. The absorbent cores of the invention comprise at leastone absorbent structure as claimed, and a second substrate to form acore wrap enclosing the absorbent material and optionally furthercomponents. In particular an absorbent core may be formed by combiningtwo absorbent structures according to the invention, where therespective absorbent material land areas and junction areas are offsetrelative to each other so that a substantially continuous absorbentmaterial layer is formed in the absorbent core.

As used herein, the term “absorbent article” refers to disposableproducts such as infant diapers (as exemplarily shown on FIG. 12),feminine pads, training pants, adult incontinence products and the likewhich are placed against or in proximity to the body of a wearer toabsorb and contain the various exudates discharged from the body.Typically absorbent articles comprise a topsheet, a backsheet, anabsorbent core and optionally an acquisition layer and/or distributionlayer, and other components, with the absorbent core normally placedbetween the backsheet and the acquisition system or topsheet. Theabsorbent core is typically the component of the absorbent article whichcomprises all, or at least the majority of, the superabsorbent polymer(SAP) and has the most absorbent capacity of all the components of theabsorbent article. The absorbent core typically comprises an absorbentmaterial enclosed in a core wrap formed by two substrates.

As used herein, the terms “comprise(s)” and “comprising” are open-ended;each specifies the presence of the feature that follows, e.g. acomponent, but does not preclude the presence of other features, e.g.elements, steps, components known in the art or disclosed herein. Theseterms based on the verb “comprise” should be read as encompassing thenarrower terms “consisting essentially of” which excludes any element,step or ingredient not mentioned which materially affect the way thefeature performs its function, and the term “consisting of” whichexcludes any element, step, or ingredient not specified. Any preferredor exemplary embodiments described below are not limiting the scope ofthe claims, unless specifically indicated to do so. The words“typically”, “normally”, “preferably”, “advantageously”, “in particular”and the likes also qualify features which are not intended to limit thescope of the claims unless specifically indicated to do so.

Unless indicated otherwise, the description refers to the absorbentstructure, core and article before use (i.e. dry, and not loaded with afluid) and conditioned at least 24 hours at 21° C.+/−2° C. and 50+/−20%Relative Humidity (RH).

The absorbent structures, cores and articles of the invention will befurther generally below and by way of illustration with the embodimentsexemplarily shown in the Figures, which are not considered limiting thescope of the invention unless indicated otherwise.

Absorbent Structure 70

FIG. 1 shows a schematic top view of an absorbent structure 70 accordingto the invention with the fibrous thermoplastic adhesive layer 74partially removed to better show the underlying absorbent materialpattern of land areas 75 and absorbent material-free junction areas 76,the auxiliary glue 72 and the substrate 16. These individual componentsand their relations are further discussed below. The absorbent structurehas a front edge 700 and a back edge 702. The front edge is the edge ofthe structure intended to be placed towards the front of the articlewhen the absorbent structure has been integrated in an absorbentarticle. The back edge is the edge of the structure opposite the frontedge. In case of doubt, the front edge may be in general towards theside of the structure with the most absorbent material. The length L ofthe substrate is measured along the longitudinal direction between thefront and back edges. The structure can be virtually divided in threethirds, a front third 38 starting from the font edge 700, a back third36 starting from the back edge 702 and a central third in-between, eachthird defined has having a length of a third of L (L/3), as shown inFIG. 1.

Substrate 16

The substrate 16 is substantially planar and extends in a transversaldirection (x) and a longitudinal direction (y). By substantially planarit is meant that the substrate can be laid flat on a surface. However,the substrate used can typically be a thin web of material of thenonwoven type which is conformable and can also be laid on a non flatsurface for example a drum during the making process of the absorbentstructure or rolled and stored as a roll of stock material before beingconverted into an absorbent structure. The substrate may also be foldedduring its processing for example to form a C-wrap longitudinal sideseal around a second substrate to enclose the absorbent material, aswill be discussed further below. For ease of discussion, the substrateis represented in FIG. 1 in a flat state and extending in a transversaldirection (x) and a longitudinal direction (y). The substrate cantypically be generally rectangular with a width W in the transversaldirection and a length L in the longitudinal direction. The width andlength of the substrate may vary depending on the intended usage. Forbaby and infant diapers, the width and length of the core may forexample be in the range from 40 mm to 200 mm for the width and 100 to500 mm for the length.

The substrate 16 may be formed by any materials suitable for receivingand containing the absorbent material. Typical substrate materials usedin the production of conventional cores may be used, in particularpaper, tissues, films, wovens or nonwovens, or laminate of any of these.The core wrap may in particular be formed by a nonwoven web, such as acarded nonwoven, spunbond nonwoven (“S”) or meltblown nonwoven (“M”),and laminates of any of these. For example spunmelt polypropylenenonwovens are suitable, in particular those having a laminate web SMS,or SMMS, or SSMMS, structure, and having a basis weight range of about 5gsm to 15 gsm. Suitable materials are for example disclosed in U.S. Pat.No. 7,744,576, US 2011/0268932 A1, US 2011/0319848 A1 and US2011/0250413 A1. Nonwoven materials provided from synthetic fibers maybe used, such as PE, PET and in particular PP.

As used herein, the terms “nonwoven layer” or “nonwoven web” generallymeans a manufactured sheet, web or batt of directionally or randomlyorientated fibers, bonded by friction, and/or cohesion and/or adhesion,excluding paper and products which are woven, knitted, tufted,stitch-bonded incorporating binding yarns or filaments, or felted bywet-milling, whether or not additionally needled. The fibers may be ofnatural or man-made origin and may be staple or continuous filaments orbe formed in situ. Commercially available fibers have diameters rangingfrom less than about 0.001 mm to more than about 0.2 mm and they come inseveral different forms such as short fibers (known as staple, orchopped), continuous single fibers (filaments or monofilaments),untwisted bundles of continuous filaments (tow), and twisted bundles ofcontinuous filaments (yam). Nonwoven webs can be formed by manyprocesses such as meltblowing, spunbonding, solvent spinning,electrospinning, carding and airlaying. The basis weight of nonwovenwebs is usually expressed in grams per square meter (g/m² or gsm).

The substrate may typically be commercially supplied as a roll ofmaterial web of several hundred meters of length. The roll is thenintegrated in a converting line and unrolled at high speed while theauxiliary glue, the absorbent material and the fibrous thermoplasticadhesive layer are applied on or deposited over the substrate and thenfurther converted into an absorbent core by enclosing the absorbentmaterial in a core wrap together with a second substrate. Typically themachine direction (MD) of the converting line may correspond to thelongitudinal direction (y) of the substrate and the cross-machinedirection (CD) to the transversal direction (x) of the substrate. Theabsorbent structures and/or cores may thus be typically formed corescontinuously and the structures and/or cores individualized by cuttingthem along their transversal edges 700, 702. This will be furtherexemplarily discussed in the process section further below.

Auxiliary Glue 72

An auxiliary glue 72 is applied directly over the substrate 16 on anauxiliary glue application area 71. The auxiliary glue may improve theadhesion between the first substrate 16 and both the absorbent material(in the absorbent material land areas 75) and the fibrous thermoplasticmaterial 74 (in the absorbent material-free junction areas 76). Theauxiliary glue may be for example any kind of thermoplastic hot-meltadhesives used in the field of absorbent core making. Such an adhesivegenerally includes one or more polymers to provide cohesive strength(e.g., aliphatic polyolefins such as ethylene-propylene copolymers,polyetheramides, polyetheresters, and combinations thereof; ethylenevinyl acetate copolymers; styrene-butadiene or styrene-isoprene blockcopolymers; etc.), a resin or analogous material (sometimes called atackifier) to provide adhesive strength (e.g., hydrocarbons distilledfrom petroleum distillates; rosins and/or rosin esters; terpenesderived, for example, from wood or citrus, etc.); and optional waxes,plasticizers or other materials to modify viscosity (e.g., mineral oil,polybutene, paraffin oils, ester oils, and the like), and/or otheradditives including, but not limited to, antioxidants or otherstabilizers. The same raw material as those discussed below in detailsfor the fibrous thermoplastic adhesive layer 74 may in particular beused, an exemplary commercial adhesive being available from Fuller undercode 1286 or 1358.

The auxiliary glue can be applied on the substrate by any adhesiveapplicator known in the field, in particular bead, slot or spraynozzles. The auxiliary glue may be in principle applied as a continuousfilm on the whole of the auxiliary glue application area 71, howeverthis may unduly increase the usage of adhesive material. The adhesivemay thus be advantageously applied discontinuously to maximize the areacovered with a lower amount of adhesive. The auxiliary glue may thus beapplied as a relatively wide curtain of adhesive using as a spraynozzle. The auxiliary glue may also be applied discontinuously as apattern of discrete application zones within the application area 72.For example, the auxiliary glue can be applied using a slot coatingprocess as a pattern comprising a plurality of spaced-apart slots whichmay each extend in the longitudinal direction, as represented in FIGS.1-2 by the slots 72. The slots may for example have a width of from 0.5mm to 3 mm, and/or have a transversal spacing therebetween of from 0.5mm to 4 mm. The slots may all be of equal length as represented in FIG.1, but may also have varying length. For example if the absorbentmaterial was also profiled transversally with more material towards thetransversal center of the substrate, it may be beneficial to have longeror wider slots towards this center of the substrate. In the example ofFIG. 1, the absorbent material is not profiled in the transversaldirection. The adhesive material slots 72 in this example are regularlyspaced and all have the same length and width. Each slot may be appliedcontinuously in the longitudinal direction as represented in FIG. 1 butthey may also be applied discontinuously. The slots may all have thesame length or may have different lengths, in case more immobilizationwas requested in some areas. When applied as slots, the auxiliary glue72 in the slots may for example be applied at a basis weight in therange from 1 gsm to 20 gsm, in particular from 2 gsm to 10 gsm, forexample 3 or 4 gsm. More generally, considering the auxiliary glueapplication 71 as a whole, with any areas free of glue between the slotsor any areas free of glue within for example the lines of a spiral glueapplication, the basis weight over the whole application area may forexample be half the basis weight indicated above for the slots 72. Thebasis weight may also vary locally within the auxiliary glue applicationarea 71.

The “auxiliary glue application area” as used herein means the smallestarea 71 in the plane of the substrate whose periphery encompasses theauxiliary glue, including any areas free of adhesive between anydiscrete auxiliary glue application zones if present. In the example ofFIG. 1, this is a rectangular area which encompasses the slots 72 aswell as the areas between the slots. The auxiliary glue application area71 may have any shape adapted to the intended usage of the absorbentarticle and the distribution of absorbent material. In particular, theauxiliary glue application area may be rectangular, shaped with atapering in the central region of the substrate, or with a centralelongated portion and shorter side portions. It is also possible thatthe auxiliary glue application area comprise separated sub-areas. Asub-area is hereby defined as an adhesive application area separatedfrom another by more than 10 mm. In that case the adhesive free areabetween the adhesive application sub-areas is not considered to be partof the auxiliary glue application area, for example for thedetermination of the basis weight of the auxiliary glue. Alternativeshapes and positions of the area 71 are exemplified in FIGS. 8-11discussed further below.

Absorbent Material

The absorbent material comprises a relative high amount ofsuperabsorbent polymer (“SAP”) particles. The absorbent materialcomprises at least 80%, in particular at least 85%, 90%, 95% and up to100%, of superabsorbent polymer particles by weight of the absorbentmaterial. The absorbent material may in particular comprise no or onlysmall amount of cellulose fibers, such as less than 20%, in particularless than 10%, 5% or even 0% of cellulose fibers by weight of theabsorbent material. The absorbent material may thus advantageouslyconsist or consist essentially of superabsorbent polymer particles.

The terms “superabsorbent polymer particles” refer to absorbentmaterials in particulate forms which may be crosslinked polymericmaterials that can typically absorb at least 10 times their weight of anaqueous 0.9% saline solution as measured using the Centrifuge RetentionCapacity (CRC) test (EDANA method WSP 241.2-05E). The SAP may inparticular have a CRC value of more than 20 g/g, or more than 24 g/g, orof from 20 to 50 g/g, or from 20 to 40 g/g, or 24 to 30 g/g. The SAPuseful in the present invention includes a variety of water-insoluble,but water-swellable polymers capable of absorbing large quantities offluids.

The superabsorbent polymers are in particulate form so as to be flowablein the dry state and thus easily deposited on the substrate. Typicalparticulate absorbent polymer materials are made of poly(meth)acrylicacid polymers. However, starch-based particulate absorbent polymermaterials may also be used, as well polyacrylamide copolymer, ethylenemaleic anhydride copolymer, crosslinked carboxymethylcellulose,polyvinyl alcohol copolymers, crosslinked polyethylene oxide, and starchgrafted copolymer of polyacrylonitrile. The superabsorbent polymer maybe polyacrylates and polyacrylic acid polymers that are internallyand/or surface crosslinked. Suitable materials are described in WO07/047598, WO 07/046052, WO 2009/155265 and WO 2009/155264. In someembodiments, suitable superabsorbent polymer particles may be obtainedby current state of the art production processes as is more particularlyas described in WO 2006/083584. The superabsorbent polymers arepreferably internally crosslinked, i.e. the polymerization is carriedout in the presence of compounds having two or more polymerizable groupswhich can be free-radically copolymerized into the polymer network. Insome embodiments, the SAP are formed from polyacrylic acidpolymers/polyacrylate polymers, for example having a neutralizationdegree of from 60% to 90%, or about 75%, having for example sodiumcounter ions.

The SAP particles may be relatively small (under 1 mm in their longestdimension) in their dry state and may be roughly circular in shape, butgranules, fibers, flakes, spheres, powders, platelets and other shapesand forms are also known to persons skilled in the art. Typically, theSAP is in the form of spherical-like particles. In contrast to fibers,“spherical-like particles” have a longest and a smallest dimension witha particulate ratio of longest to smallest particle dimension in therange of 1-5, where a value of 1 would equate a perfectly sphericalparticle and 5 would allow for some deviation from such a sphericalparticle. The superabsorbent polymer particles may have a particle sizeof less than 850 μm, or from 50 to 850 μm, preferably from 100 to 710μm, more preferably from 150 to 650 μm, as measured according to EDANAmethod WSP 220.2-05. SAP having a relatively low particle size help toincrease the surface area of the absorbent material which is in contactwith liquid exudates and therefore support fast absorption of liquidexudates.

The absorbent core will typically comprise only one type of SAP, but itis not excluded that a blend of SAPs may be used. The fluid permeabilityof a superabsorbent polymer can be quantified using its UrinePermeability Measurement (UPM) value, as measured in the test disclosedEuropean patent application number EP 12174117.7. The UPM of the SAP mayfor example be of at least 10×10⁻⁷ cm³·sec/g, or at least 30×10⁻⁷cm³·sec/g, or at least 50×10⁻⁷ cm³·sec/g, or more, e.g. at least 80 or100×10⁻⁷ cm³·sec/g. The flow characteristics can also be adjusted byvarying the quantity and distribution of the SAP used in the secondabsorbent layer.

The absorbent material is deposited on the substrate 16 in a patternhaving absorbent material land areas 75 separated by absorbentmaterial-free junction areas 76. Examples of such a pattern have beendescribed in details for example in WO2008/155699. In the examplerepresented in FIG. 1, the absorbent material land areas 75 are ofgenerally rectangular shape in the plane of the substrate with thelongest side orientated in the transversal direction. The structure maycomprise for example between 5 and 30 of these generally rectangularland areas 75. These land areas may have for example a width rangingfrom 4 to 20 mm, in particular 10 mm, as measured in the longitudinaldirection (y). The land areas 75 may be of uniform width but they mayhave different width, in particular towards the center or crotch sectionof the absorbent structure to form so called “dog bone” or “hour-glass”shape, which shows a tapering along its width at least in the crotchzone of the structure. The junction areas 76 between the land areas 75may have a width exemplarily ranging from 0.5 to 10 mm, for example 1 to5 mm. Of course other patterns of deposition of the absorbent materialare possible, thus for example as an array of circular or ovoid landareas, or combination of rectangular land areas with circular or ovoidland areas.

In many applications, the liquid discharge occurs predominantly in onearea of the core. For diapers, the liquid may predominantly be releasedtowards the central zone 37 (also called crotch area) of the core and toa lesser extent the front 38 of the core. Relatively less liquid may bereleased towards the back 36 of the core. Thus it is may be beneficialto profile the amount of absorbent material along the longitudinaldirection of the absorbent structure so that more absorbent material ispresent in the areas where the liquid is more likely to insult the core.

As used herein, the absorbent material deposition area 73 is defined asthe smallest area in the plane of the substrate whose peripheryencompasses the land areas 75 and the junction areas 76 between the landareas. In order to quantify the amount of profiling, the absorbentmaterial deposition area 73 can be virtually divided in eight depositionzones (Z1-Z8) of equal length as measured along the longitudinaldirection of the structure. The zones may be of equal width and equalsurface if the absorbent material deposition area 73 is rectangular, butit is not excluded that the zones may have varying width for example inthe case of shaped absorbent material deposition area, e.g. having atapering towards the crotch region of the core.

The absorbent structures of the invention are profiled along thelongitudinal direction of the structure so that at least one of theeight deposition zones (Z1, Z2, Z7, Z8) is a zone of lower amount ofabsorbent material. A zone of lower absorbent material amount is definedherein as a zone having an amount of absorbent material that is at least20% by weight lower than the average amount of absorbent material in thewhole absorbent material deposition area 73 (that is the eight zonestogether). These zones of lower absorbent material amount may be presenttowards the front and/or back of the deposition area 73 as representedby zones Z1, Z2, Z7, Z8 in FIG. 1, but it is not excluded that one ormore zones of lower absorbent material amount may also be presenttowards the center of the deposition area. The zone of lower absorbentmaterial amount may further have an amount of absorbent material that isat least 40%, or 50%, or 60%, in particular ranging from 20% to 80%, byweight lower than the average amount of absorbent material in the wholeabsorbent material deposition area 73.

The zones of lower absorbent material amount require less immobilizationof the SAP than the other zones, so that less auxiliary glue is requiredin these zones. In particular, the auxiliary glue may be absent in atleast one, and advantageously all, of the zones of lower absorbentmaterial. The auxiliary glue may also be present but in an amount of atleast 50% by weight lower than the average amount of auxiliary glue inthe eight absorbent material deposition zone. The invention thus providefor the overall reduction of adhesive material usage by saving theauxiliary glue in the zones where it is less needed. The fibrousthermoplastic adhesive layer 74 may still be present in these zones oflower amount as shown in FIG. 1, to provide the required SAPimmobilization, but it is not excluded that even the fibrousthermoplastic layer may be excluded from these zones.

On the other hand, some of the absorbent material deposition zones mayalso have relatively higher amount of SAP deposited. Thus for examplethe deposition zones Z4, Z5, Z6 towards the center of the depositionarea 73 may be zones of higher absorbent material amount. Moregenerally, the absorbent structure may have at least one zone ofdeposition having an amount of absorbent material that is at least 20%higher than the average amount of absorbent material in the absorbentmaterial deposition area 73. The auxiliary glue 72 may be advantageouslypresent in at least one of these zones of higher absorbent materialamount, as these zones will be advantageously stabilized by theauxiliary glue.

The amount of absorbent material in each zone may be normally directlycalculated from the formula card of the absorbent core considered.Typically modern SAP application process allows for a reliable andreproducible application of the SAP. In case of an absorbent core madeby a third party where the formula card of the core is not available,the amount of absorbent material in each zones may be measuredanalytically using known methods. For example once the absorbentmaterial deposition area and its eight zones are determined (visually orby X-ray), each of the eight zones may be cut from the absorbent coreand each cut can then be analyzed for the amount of SAP individually byany standard methods such as titration or gravimetric analysis. The sameapplies to determine the auxiliary glue application pattern. UV lightmay be useful to determine where the glue has been applied.

The absorbent material may be deposited in the absorbent materialdeposition area 73 using known techniques, which may allow relativelyprecise deposition of SAP particles at relatively high speed. Inparticular the SAP printing technology as disclosed for example inUS2006/24433 (Blessing), US2008/0312617 and US2010/0051166A1 (both toHundorf et al.) may be used. This technique uses a printing roll todeposit SAP particles onto a substrate disposed on a grid of a supportwhich may include a plurality of cross bars extending substantiallyparallel to and spaced from one another so as to form channels extendingbetween the cross-bars. In addition to be profiled in the longitudinaldirection, the absorbent material may also be deposited at differentbasis weight in the transversal direction, so that, for example there ishigher amount of absorbent material towards the center longitudinal axisof the structure relative to its longitudinal sides.

In general, the auxiliary glue application area 71 may be smaller thanthe absorbent material deposition area 73. In particular, the surface ofthe auxiliary glue application area 71 may be no greater than 80%,optionally no greater than 70%, or no greater than 60%, or no greaterthan 50%, than the surface of the absorbent material deposition area 73,the surface being measured in the plane of the structure. The surface ofthe auxiliary glue application area 71 may be in particular in the rangeof from 20% to 80% of the surface of the absorbent material depositionarea 73.

Other Examples of Shape of the Application Area 71 and Deposition Area73

FIG. 1 shows an example where the auxiliary glue application area 71 andabsorbent material deposition area 73 are both rectangular, have aboutthe same width and wherein the application area 71 is longitudinallyshorter than the deposition area 73 and does not extend to any of thefront or back ends of the absorbent material deposition area. FIGS. 8 to11 show alternative examples of geometries for these areas, which willaddressed below. The auxiliary glue and the absorbent material may beapplied in these areas according to any of the possibilities describedabove. The individual features of these further geometry examples may becombined with any other features of other examples or of the generalsection of this description unless otherwise indicated.

FIG. 8 shows for example an auxiliary glue application area 71 whichextends from the front end of the absorbent material deposition area 73and wherein both areas have about the same width (the borders of thearea 71 have been shown slightly inwards of those of the area 73 forbetter understanding). This may be advantageous for structures having arelatively high amount of AGM towards the front of the structure, wheremore auxiliary glue may be needed. As in FIG. 1, the auxiliary glue maybe absent from at least one zone Z7, Z8 towards the back of theabsorbent material deposition area 73.

FIG. 9 shows another example, where the auxiliary glue deposition area71 is less wide than the absorbent material deposition area 73. Thisembodiment may be for example interesting when the absorbent material isapplied in a profiled way in the transversal direction with a higherbasis weight towards the longitudinal centerline of the structure. Inthis way the auxiliary glue is present where the absorbent material isin higher amount.

FIG. 10 shows another example where the absorbent material depositionarea 73 is shaped in the plane of structure so as to show a tapering inthe central zone of the structure. This may be advantageous in order toprovide a shaped core which may provide better fit of the absorbentarticle in the crotch section, for example for absorbent diaperapplication.

FIG. 11 shows another example where the auxiliary glue application areais not rectangular but has a central body with two adjoined side wings.These side wings may be larger than the central body. The wings as showndo not extend to the transversal edges of the deposition area 73 butthey may also extend to these edges if desired. These sections ofdifferent lengths may for example be easily obtained using a slotcoating process and tuning the slot nozzles to apply the hot-meltadhesive on a shorter distance on the transversal sides of theapplication area 71 compared to the lateral center of the applicationarea 71.

Fibrous Thermoplastic Adhesive Layer 74

The absorbent structure comprises a fibrous thermoplastic adhesive layer74 which covers at least some, and advantageously all, of the land areas75 and the absorbent material-free junction areas 76 in-between in orderto provide further immobilization of at least some, advantageously all,of the absorbent material on the substrate and then within the absorbentcore. The fibrous thermoplastic adhesive may be sprayed over theabsorbent material so as to cover the absorbent material land areas andjunction areas. This imparts an essentially three-dimensional structureto the fibrous layer of thermoplastic adhesive 74, which in itself isessentially a two-dimensional structure of relatively small thickness,as compared to the dimensions in length and width directions. Thereby,the fibrous thermoplastic adhesive may provide cavities to cover theabsorbent material in the land areas, and thereby immobilizes theabsorbent material, which as already indicated may be 100% SAPparticles.

The adhesive polymers useful to form the fibrous layer 74 are forexample described in WO2008/155699 starting on page 19, last paragraph.The thermoplastic adhesive may comprise, in its entirety, a singlethermoplastic polymer or a blend of thermoplastic polymers, having asoftening point, as determined by the ASTM Method D-36-95 “Ring andBall”, in the range between 50° C. and 300° C., and/or the thermoplasticadhesive material may be a hot-melt adhesive comprising at least onethermoplastic polymer in combination with other thermoplastic diluentssuch as tackifying resins, plasticizers and additives such asantioxidants.

The thermoplastic polymer may typically have a molecular weight (Mw) ofmore than 10,000 and a glass transition temperature (Tg) usually belowroom temperature or −6° C.<Tg<16° C. Typical concentrations of thepolymer in a hot-melt are in the range of about 20 to about 40% byweight. The thermoplastic polymers may be water insensitive. Exemplarypolymers are (styrenic) block copolymers including A-B-A triblockstructures, A-B diblock structures and (A-B)n radial block copolymerstructures wherein the A blocks are non-elastomeric polymer blocks,typically comprising polystyrene, and the B blocks are unsaturatedconjugated diene or (partly) hydrogenated versions of such. The B blockis typically isoprene, butadiene, ethylene/butylene (hydrogenatedbutadiene), ethylene/propylene (hydrogenated isoprene), and mixturesthereof. Other suitable thermoplastic polymers that may be employed aremetallocene polyolefins, which are ethylene polymers prepared usingsingle-site or metallocene catalysts. Therein, at least one comonomercan be polymerized with ethylene to make a copolymer, terpolymer orhigher order polymer. Also applicable are amorphous polyolefins oramorphous polyalphaolefins (APAO) which are homopolymers, copolymers orterpolymers of C2 to C8 alpha olefins.

The tackifying resin may exemplarily have a Mw below 5,000 and a Tgusually above room temperature, typical concentrations of the resin in ahot-melt are in the range of about 30 to about 60%, and the plasticizerhas a low Mw of typically less than 1,000 and a Tg below roomtemperature, with a typical concentration of about 0 to about 15%.

The thermoplastic adhesive of the thermoplastic material layer 74, 74′is applied as fibers. The fibers may exemplarily have an averagethickness of about 1 to about 50 micrometers or about 1 to about 35micrometers and an average length of about 5 mm to about 50 mm or about5 mm to about 30 mm. The thermoplastic adhesive of the thermoplasticmaterial layer 74, 74′ may be applied with a basis weight in the rangefrom 2 gsm to 20 gsm, optionally from 2 gsm to 10 gsm, for example 3 or4 gsm.

The thermoplastic adhesive used for the thermoplastic material layer 74,74′ may have elastomeric properties, such that a fibrous layer formed onthe SAP layer is able to be stretched as the SAP swells. Exemplaryelastomeric, hot-melt adhesives include thermoplastic elastomers such asethylene vinyl acetates, polyurethanes, polyolefin blends of a hardcomponent (generally a crystalline polyolefin such as polypropylene orpolyethylene) and a soft component (such as ethylene-propylene rubber);copolyesters such as poly (ethylene terephthalate-co-ethylene azelate);and thermoplastic elastomeric block copolymers having thermoplastic endblocks and rubbery mid blocks designated as A-B-A block copolymers;mixtures of structurally different homopolymers or copolymers, e.g., amixture of polyethylene or polystyrene with an A-B-A block copolymer;mixtures of a thermoplastic elastomer and a low molecular weight resinmodifier, e.g., a mixture of a styrene-isoprenestyrene block copolymerwith polystyrene; and the elastomeric, hot-melt, pressure-sensitiveadhesives described herein. Elastomeric, hot-melt adhesives of thesetypes are described in more detail in U.S. Pat. No. 4,731,066 (Korpman).A commercial example of elastomeric hot-melt adhesive suitable is FullerNW1151.

The thermoplastic adhesive used for the auxiliary glue 72 may or may notcomprise any of the adhesive types described above in relation to thethermoplastic fibrous adhesive layer 74. The auxiliary glue 72 may bethe same or different as the adhesive of the fibrous thermoplasticadhesive 74. The adhesives are preferably selected for theircompatibility, so that the auxiliary glue can also serve to improve theadhesion of the fibrous adhesive layer 74 to the substrate 16. Using thesame basic adhesive formulation for both layers may be advantageous interms of adherence performance but it may also be preferred to use acheaper adhesive for the auxiliary glue as elastomeric properties maynot be advantageous for the auxiliary glue layer.

Absorbent Core 28

Although the absorbent structure 70 of the invention may be useddirectly in an absorbent article without further assembly, the absorbentstructure may typically be assembled with other components to form anabsorbent core before being introduced in an absorbent article. Such anabsorbent core 28 comprises a second substrate 16′ placed in face toface relationship with the first substrate 16 to form a core wrap whichdefines the external surfaces of the core. The two substrates may thusform a core wrap enclosing the absorbent material of the core.

The absorbent core 28 may typically be generally substantially flat in aplane being the same as the plane formed by the longitudinal direction xand transversal direction y of the substrate 16. The absorbent core willtypically be thin, being thus understood that the FIGS. 3 to 7 areschematic and shows an exaggeration of the inner layer of thestructure/core in the vertical direction. In particular, the maximumcaliper of the core (before use) as measured according to the CoreCaliper Test as described herein may be from 0.25 mm to 5.0 mm, inparticular from 0.5 mm to 4.0 mm. The full length L′ of the core may bethe same length as the length of any or both of the substrates, and canbe measured from the core's front edge 280 to its back edge 282 alongits central longitudinal axis. It may for example be at least 320 mm,for example from 320 mm to 600 mm, for typical diaper applications, butmay be shorter for smaller articles.

The substrates may be comprise at least one, typically two, transversalend seals 280, 282 and at least one, typically two, longitudinal sideseals 284, 286, wherein the seals can be continuous or discontinuousalong their lengths. Typically the absorbent material will beadvantageously distributed in somewhat higher amount towards the frontedge 280 than towards the back edge as more absorbency is required atthe front of the core (assuming the front of core will be placed towardsthe front of the article). Typically the front and back edges of thecore are shorter than the longitudinally extending side edges of thecore. The absorbent core 28 may also comprise a top side and a bottomside, which are substantially concomitant with the external surfaces ofthe first and second substrate or vice versa.

FIG. 4 shows a cross-section of an absorbent core 28 comprising anabsorbent structure 70 assembled directly with a second substrate 16′.The second substrate may be made of the same material as the substrate16. Typically, the side of the core intended to be placed towards thewearer in the finished absorbent article will be hydrophillicallytreated and the side of the core placed towards the backsheet may beinherently hydrophobic or hydrophobically treated, so that the liquidcan more easily penetrate into and remain inside the core.

It may be advantageous that the absorbent core comprises a secondabsorbent structure 70′ comprising a second absorbent material, asexemplarily represented in FIGS. 5 and 6. The second absorbent structuremay or may not be a structure according to the invention, in particularit may or may not comprise a secondary auxiliary glue 72′. The secondabsorbent material may also be deposited on the second substrate 16′ ina pattern of absorbent material land areas 75′ separated by absorbentmaterial-free junction areas 76′. When the first and second absorbentstructures are combined together to form the core, the respectivepatterns of land areas and junction areas of the absorbent structuresmay be advantageously placed offset from each other so that theabsorbent material placed between the substrates form an absorbentparticulate polymer area layer 8 which is substantially continuous. Sucha dual composite structure of matching land areas and junction areas isfor example disclosed in WO2008/155699 (Hundorf).

The second absorbent structure 70′ may thus comprise a second substrate16′, a second absorbent material comprising from 80% to 100% by weightof superabsorbent particles and deposited on the substrate in a patternof absorbent material land areas 75′ separated by absorbentmaterial-free junction areas 76′, a second fibrous thermoplasticadhesive layer 74′ arranged to cover at least some of the land areas 75′and the absorbent material-free junction areas 76′ to thereby immobilizeat least some of the second absorbent material on the second substrate,and a optionally a second auxiliary glue 72′ applied directly over thesecond substrate. However, other patterns are possible includingso-called islands-in-the-sea arrangements with either the absorbentmaterial areas or the absorbent material-free areas defining theislands, as described in US2008/0312622 A1 (Hundorf), for example. Thesecond absorbent material could, alternatively, take other forms, suchas a mixed layer of cellulose-based absorbent material andsuperabsorbent material.

If present, the second auxiliary glue 72′ may be applied across alimited length of the second of substrate as shown on FIG. 5. The secondabsorbent structure may then also be an absorbent structure according tothe first aspect of the invention, wherein the second absorbent materialdeposition area can be notionally divided in eight deposition zones ofequal length along its longitudinal direction; and having at least onedeposition zones of lower absorbent material amount having an amount ofabsorbent material that is at least 20% by weight lower than the averageamount of absorbent material in the whole second absorbent materialdeposition area and wherein the auxiliary glue 72′ is absent or inreduced amount in at least one of these deposition zones of lowerabsorbent material amount. The second absorbent material deposition areais defined similarly as the first absorbent material deposition area andis the smallest area in the plane of the second substrate 16′ whoseperiphery encompasses the land areas 75′ and the junction areas 76′between the land areas.

The second absorbent structure may alternatively also have no auxiliaryglue 72′ directly applied on the second substrate 16′, as exemplarilyshown on FIG. 6. This provides further material savings and mayrepresent an appropriate compromise if the first auxiliary glue layertogether with the fibrous thermoplastic layers 74, 74′ provide enoughSAP immobilization.

FIG. 7 shows a schematic cross-section of the core of FIG. 6. It is tobe understood that the fibrous adhesive layer is shown in this view inexaggerated form and that in reality the second substrate 16′ wouldappear in contact with the absorbent material in the land areas 75. Ingeneral, the core wrap formed by the substrates 16, 16′ may be sealedalong its front edge 280 and back edge 282. FIG. 7 further shows typicalso-called C-wrap seals 284, 286 along each of the longitudinal side edgeof the core, wherein one of the substrate forms a transversallyextending flap along each side edge of the core, each flap being foldedaround an edge of the core and then attached to the external surface ofthe other substrate on the other side of the core. The C-wrap seal canbe typically be formed by providing one of the substrate with a largerwidth than the second substrate, applying an adhesive along each of thetransversal edges of the larger substrate and then folding these twoextending flaps over the longitudinal edges of the core and unto theexternal surface of the other substrate. The adhesive applied providesfor a secure seal along the edges of the core that have been C-wrapped,typically the longitudinal edges. The C-wrap seals may typically beglued but other bonding means are not excluded. The front edge seal 280and back edge seal 282 of the core may be performed by any known means,in a particular in a sandwich wrap configuration as shown on FIG. 5 andFIG. 6 wherein the internal surfaces of the two substrates are bonded toeach other on a face to face relationship. The front and backtransversal seals may use gluing, e.g. using a series of glue lineslongitudinally oriented, or hot crimping. The seals of the core wrap mayalso be provided by any other conventional means and may be intermittentor continuous.

The absorbent cores and structure of the invention may comprise one ormore channels partially oriented in the longitudinal direction, asexemplarily disclosed in WO2012/170778 (Rosati et al., see alsoWO2012/170779, WO2012/170781 and WO2012/170808. The absorbent core andstructures of the invention may also be devoid of such channels. Thechannels may be formed in various ways. For example, the channels may beformed by openings within the absorbent material layer inside the corewrap. The channels may be substantially or completely free of absorbentmaterial, in particular SAP. In addition or alternatively, the channelsmay be formed by continuously or discontinuously bonding the firstsubstrate to the second substrate through the absorbent material layerin areas substantially free of absorbent material. The substrates inthese channels may be continuously or discontinuously bonded to eachother. Other layers between the topsheet 24 and the absorbent core 28may or may not also comprise channels, which may or may not correspondto the channels of the absorbent core 28. The absorbent core may alsonot comprise any of such channels.

The total amount of SAP present in the absorbent core may also varyaccording to expected usage. Diapers for newborns may require less SAPthan infant or adult incontinence diapers. The amount of SAP in the coremay be for example comprised from about 5 to 60 g, in particular from 10to 25 g. The average SAP basis weight within the absorbent materiallayer 8 within the core may be for example of at least 50, 100, 200,300, 400, 500 or more g/m². The absorbent core may further alsoadvantageously achieve an SAP loss of no more than about 70%, 60%, 50%,40%, 30%, 20%, or 10% according to the Wet Immobilization Test describedin WO 2010/0051166 A1.

General Description of the Absorbent Article 20

The absorbent core comprising the absorbent structure of the inventionor the absorbent structure itself will typically be used in an absorbentarticle. An exemplary absorbent article in the form of an infant diaper20 is represented in FIG. 12. FIG. 12 is a top plan view of theexemplary diaper 20, in a flat-out state, with portions of the structurebeing cut-away to more clearly show the construction of the diaper 20.This diaper 20 is shown for illustration purpose only as the inventionmay be used for making a wide variety of diapers or other absorbentarticles.

The absorbent article 20 comprises a liquid permeable topsheet 24, aliquid impermeable backsheet 25 and an absorbent core 28 positionedbetween the topsheet 24 and the backsheet 25. The absorbent article mayalso comprise further typical components such as an acquisition layer 52and/or a distribution layer 54 (collectively referred to asacquisition-distribution system “ADS”), and elasticized gasketing cuffs32 present between topsheet and backsheet and upstanding barrier legcuffs 34, which will be further detailed in the following. FIG. 12 alsoshow other typical taped diaper components such as a fastening systemcomprising fastening tabs 42 attached towards the back edge 12 of thearticle and cooperating with a landing zone 44 towards the front edge ofthe article. The absorbent article may also comprise other typicalcomponents, which are not represented in the Figures, such as a backelastic waist feature, a front elastic waist feature, transverse barriercuffs, a lotion application, etc.

The absorbent article 20 comprises a front edge 10, a back edge 12, andtwo side edges. The front edge 10 is the edge of the article which isintended to be placed towards the front of the user when worn, and theback edge 12 is the opposite edge. The absorbent article may benotionally divided by a longitudinal axis 80 extending from the frontedge to the back edge of the article and dividing the article in twosubstantially symmetrical halves relative to this axis, when viewing thearticle from the wearer facing side in a flat out configuration, asexemplarily shown in FIG. 12. If some part of the article is undertension due to elasticized components, the article may be typicallyflattened using clamps along the periphery of the article and/or asticky surface, so that the topsheet and backsheet can be pulled taut soas to be substantially flat. Unless otherwise indicated, dimensions andareas disclosed herein apply to the article in this flat-outconfiguration.

The absorbent article 20 can also be notionally divided by a transversalaxis 90 into a front region and a back region of equal length measuredon the longitudinal axis, when the article is in such a flat state. Thisarticle's transversal axis 90 is perpendicular to the longitudinal axis80 and placed at half the length of the article. The length of thearticle can be measured along the longitudinal axis 80 from front edge10 to back edge 12.

The topsheet 24, the backsheet 25, the absorbent core 28 and the otherarticle components may be assembled in a variety of well-knownconfigurations, in particular by gluing and/or heat embossing. Exemplarydiaper assemblies are for example generally described in U.S. Pat. No.3,860,003, U.S. Pat. Nos. 5,221,274, 5,554,145, 5,569,234, 5,580,411,and 6,004,306. The absorbent article is preferably thin. The article maybe advantageously thin at the intersection of the longitudinal andtransversal axes, for example with a caliper of from 1.0 mm to 8.0 mm,in particular from 1.5 mm to 6.0 mm, as measured using the AbsorbentArticle Caliper Test described below.

Topsheet 24

The topsheet 24 is the part of the absorbent article 20 that is directlyin contact with the wearer's skin. The topsheet 24 can be joined to thebacksheet 25, the absorbent core 28 and/or any other layers as is knownin the art (as used herein, the term “joined” encompasses configurationswhereby an element is directly secured to another element by affixingthe element directly to the other element, and configurations whereby anelement is indirectly secured to another element by affixing the elementto intermediate member(s) which in turn are affixed to the otherelement). Usually, the topsheet 24 and the backsheet 25 are joineddirectly to each other in some locations (e.g. on or close to theperiphery of the article) and are indirectly joined together in otherlocations by directly joining them to one or more other elements of thearticle 20.

The topsheet 24 is preferably compliant, soft-feeling, andnon-irritating to the wearer's skin. Further, at least a portion of thetopsheet 24 is liquid permeable, permitting liquids to readily penetratethrough its thickness. A suitable topsheet may be manufactured from awide range of materials, such as porous foams, reticulated foams,apertured plastic films, or woven or nonwoven materials of naturalfibers (e.g., wood or cotton fibers), synthetic fibers or filaments(e.g., polyester or polypropylene or bicomponent PE/PP fibers ormixtures thereof), or a combination of natural and synthetic fibers. Ifthe topsheet 24 includes fibers, the fibers may be spunbond, carded,wet-laid, meltblown, hydroentangled, or otherwise processed as is knownin the art, in particular spunbond PP nonwoven. A suitable topsheetcomprising a web of staple-length polypropylene fibers is manufacturedby Veratec, Inc., a Division of International Paper Company, of Walpole,Mass. under the designation P-8.

Suitable formed film topsheets are also described in U.S. Pat. Nos.3,929,135, 4,324,246, 4,342,314, 4,463,045, and 5,006,394. Othersuitable topsheets may be made in accordance with U.S. Pat. Nos.4,609,518 and 4,629,643. Such formed films are available from TheProcter & Gamble Company of Cincinnati, Ohio as “DRI-WEAVE” and fromTredegar Corporation, based in Richmond, Va., as “CLIFF-T”.

Any portion of the topsheet may be coated with a lotion as is known inthe art. Examples of suitable lotions include those described in U.S.Pat. Nos. 5,607,760, 5,609,587, 5,643,588, 5,968,025 and 6,716,441. Thetopsheet 24 may also include or be treated with antibacterial agents,some examples of which are disclosed in WO 95/24173. Further, thetopsheet, the backsheet or any portion of the topsheet or backsheet maybe embossed and/or matte finished to provide a more cloth likeappearance.

The topsheet 24 may comprise one or more apertures to ease penetrationof exudates therethrough, such as urine and/or feces (solid, semi-solid,or liquid). The size of at least the primary aperture is important inachieving the desired waste encapsulation performance. If the primaryaperture is too small, the waste may not pass through the aperture,either due to poor alignment of the waste source and the aperturelocation or due to fecal masses having a diameter greater than theaperture. If the aperture is too large, the area of skin that may becontaminated by “rewet” from the article is increased. Typically, thetotal area of the apertures at the surface of a diaper may have an areaof between about 10 cm² and about 50 cm², in particular between about 15cm² and 35 cm². Examples of apertured topsheet are disclosed in U.S.Pat. No. 6,632,504. WO 2011/163582 also discloses suitable coloredtopsheet having a basis weight of from 12 to 18 gsm and comprising aplurality of bonded points. Each of the bonded points has a surface areaof from 2 mm² to 5 mm² and the cumulated surface area of the pluralityof bonded points is from 10 to 25% of the total surface area of thetopsheet. Typical diaper topsheets have a basis weight of from about 10to about 28 gsm, in particular between from about 12 to about 18 gsm butother basis weights are possible.

Backsheet 25

The backsheet 25 is generally that portion of the absorbent article 20which forms the external surface of the article when worn by the user.The backsheet 25 is positioned towards the bottom side of the absorbentcore 28 and prevents the exudates absorbed and contained therein fromsoiling articles such as bed sheets and undergarments. The backsheet 25is typically impermeable to liquids (e.g. urine). The backsheet 25 mayfor example be or comprise a thin plastic film such as a thermoplasticfilm having a thickness of about 0.012 mm to about 0.051 mm. Exemplarybacksheet films include those manufactured by Tredegar Corporation,based in Richmond, Va., and sold under the trade name CPC2 film. Othersuitable backsheet materials may include breathable materials whichpermit vapors to escape from the article 20 while still preventingexudates from passing through the backsheet 25. Exemplary breathablematerials may include materials such as woven webs, nonwoven webs,composite materials such as film-coated nonwoven webs, microporous filmssuch as manufactured by Mitsui Toatsu Co., of Japan under thedesignation ESPOIR NO and by Tredegar Corporation of Richmond, Va., andsold under the designation EXAIRE, and monolithic films such asmanufactured by Clopay Corporation, Cincinnati, Ohio under the nameHYTREL blend P18-3097. Some breathable composite materials are describedin greater detail in WO 95/16746 (E. I. DuPont), U.S. Pat. No. 5,938,648(LaVon et al.), U.S. Pat. No. 4,681,793 (Linman et al.), U.S. Pat. No.5,865,823 (Curro), U.S. Pat. No. 5,571,096 (Dobrin et al.) and U.S. Pat.No. 6,946,585 (London Brown).

The backsheet 25 may be joined to the topsheet 24, the absorbent core 28or any other element of the diaper 20 by any attachment means known inthe art. Suitable attachment means are described above with respect tomeans for joining the topsheet 24 to other elements of the article 20.For example, the attachment means may include a uniform continuous layerof adhesive, a patterned layer of adhesive, or an array of separatelines, spirals, or spots of adhesive. Suitable attachment meanscomprises an open pattern network of filaments of adhesive as disclosedin U.S. Pat. No. 4,573,986. Other suitable attachment means includeseveral lines of adhesive filaments which are swirled into a spiralpattern, as is illustrated by the apparatus and methods shown in U.S.Pat. Nos. 3,911,173, 4,785,996; and 4,842,666. Adhesives which have beenfound to be satisfactory are manufactured by H. B. Fuller Company of St.Paul, Minn. and marketed as HL-1620 and HL 1358-XZP. Alternatively, theattachment means may comprise heat bonds, pressure bonds, ultrasonicbonds, dynamic mechanical bonds, or any other suitable attachment meansor combinations of these attachment means as are known in the art.

Acquisition-Distribution System

The absorbent articles of the invention may comprise an acquisitionlayer 52, a distribution layer 54, or combination of both (hereincollectively referred to as acquisition-distribution system “ADS”). Thefunction of the ADS is typically to quickly acquire the fluid anddistribute it to the absorbent core in an efficient manner. The ADS maycomprise one, two or more layers, which may form a unitary layer orremain discrete layers which may be attached to each other. In theexamples below, the ADS comprises two layers: a distribution layer 54and an acquisition layer 52 disposed between the absorbent core and thetopsheet, but the invention is not restricted to this example.

Typically, the ADS will not comprise SAP as this may slow theacquisition and distribution of the fluid. The prior art discloses manytype of acquisition-distribution system, see for example WO 2000/59430(Daley), WO 95/10996 (Richards), U.S. Pat. No. 5,700,254 (McDowall), WO02/067809 (Graef). The ADS may, although not necessarily, comprise twolayers: a distribution layer 54 and an acquisition layer 52, which willnow be exemplified in more detail.

Distribution Layer 54

The function of a distribution layer 54 is to spread the insulting fluidliquid over a larger surface within the article so that the absorbentcapacity of the core can be more efficiently used. Typically thedistribution layer is made of a nonwoven material based on synthetic orcellulosic fibers and having a relatively low density. The density ofthe distribution layer may vary depending on the compression of thearticle, but may typically range from 0.03 to 0.25 g/cm³, in particularfrom 0.05 to 0.15 g/cm³ measured at 0.30 psi (2.07 kPa). Thedistribution layer 54 may also be a material having a water retentionvalue of from 25 to 60, preferably from 30 to 45, measured as indicatedin the procedure disclosed in U.S. Pat. No. 5,137,537. The distributionlayer 54 may typically have an average basis weight of from 30 to 400g/m², in particular from 100 to 300 g/m².

The distribution layer 54 may for example comprise at least 50% byweight of crosslinked cellulose fibers. The crosslinked cellulosicfibers may be crimped, twisted, or curled, or a combination thereofincluding crimped, twisted, and curled. This type of material has beenused in the past in disposable diapers as part of an acquisition system,for example US 2008/0312622 A1 (Hundorf). The crosslinked cellulosicfibers provide higher resilience and therefore higher resistance againstthe compression in the product packaging or in use conditions, e.g.under baby weight.

Exemplary chemically crosslinked cellulosic fibers suitable for adistribution layer are disclosed in U.S. Pat. Nos. 5,549,791, 5,137,537,WO 95/34329 or US 2007/118087. Exemplary crosslinking agents includepolycarboxylic acids such as citric acid and/or polyacrylic acids suchas acrylic acid and maleic acid copolymers. For example, the crosslinkedcellulosic fibers may have between about 0.5 mole % and about 10.0 mole% of a C2-C9 polycarboxylic acid crosslinking agent, calculated on acellulose anhydroglucose molar basis, reacted with said fibers in anintrafiber ester crosslink bond form. The C2-C9 polycarboxylic acidcrosslinking agent may be selected from the group consisting of:

-   -   aliphatic and alicyclic C2-C9 polycarboxylic acids having at        least three carboxyl groups per molecule; and    -   aliphatic and alicyclic C2-C9 polycarboxylic acids having two        carboxyl groups per molecule and having a carbon-carbon double        bond located alpha, beta to one or both of the carboxyl groups,        wherein one carboxyl group in said C2-C9 polycarboxylic acid        crosslinking agent is separated from a second carboxyl group by        either two or three carbon atoms. The fibers may have in        particular between about 1.5 mole % and about 6.0 mole %        crosslinking agent, calculated on a cellulose anhydroglucose        molar basis, reacted therewith in the form of intrafiber ester        crosslink bonds. The crosslinking agent may be selected from the        group consisting of citric acid, 1,2,3,4 butane tetracarboxylic        acid, and 1,2,3 propane tricarboxylic acid, in particular citric        acid.

Polyacrylic acid crosslinking agents may also be selected frompolyacrylic acid homopolymers, copolymers of acrylic acid, and mixturesthereof. The fibers may have between 1.0 weight % and 10.0 weight %,preferably between 3 weight % and 7 weight %, of these crosslinkingagents, calculated on a dry fiber weight basis, reacted therewith in theform of intrafiber crosslink bonds. The crosslinking agent may be apolyacrylic acid polymer having a molecular weight of from 500 to40,000, preferably from 1,000 to 20,000. The polymeric polyacrylic acidcrosslinking agent may be a copolymer of acrylic acid and maleic acid,in particular wherein the weight ratio of acrylic acid to maleic acid isfrom 10:1 to 1:1, preferably from 5:1 to 1.5:1. An effective amount ofcitric acid may be further mixed with said polymeric polyacrylic acidcrosslinking agent.

The distribution layer 54 comprising crosslinked cellulose fibers maycomprise other fibers, but this layer may advantageously comprise atleast 50%, or 60%, or 70%, or 80%, or 90% or even up to 100%, by weightof the layer, of crosslinked cellulose fibers (including thecrosslinking agents). Examples of such mixed layer of crosslinkedcellulose fibers may comprise about 70% by weight of chemicallycrosslinked cellulose fibers, about 10% by weight polyester (PET)fibers, and about 20% by weight untreated pulp fibers. In anotherexample, the layer of crosslinked cellulose fibers may comprise about70% by weight chemically crosslinked cellulose fibers, about 20% byweight lyocell fibers, and about 10% by weight PET fibers. In anotherexample, the layer may comprise about 68% by weight chemicallycrosslinked cellulose fibers, about 16% by weight untreated pulp fibers,and about 16% by weight PET fibers. In another example, the layer ofcrosslinked cellulose fibers may comprise from about 90-100% by weightchemically crosslinked cellulose fibers.

Acquisition Layer 52

The absorbent article 20 may comprise an acquisition layer 52, whosefunction is to quickly acquire the fluid away from the topsheet so as toprovide a good dryness for the wearer. The acquisition layer 52 istypically placed directly under the topsheet. If present, thedistribution layer 54 may be at least partially disposed under theacquisition layer 52. The acquisition layer may typically be or comprisea non-woven material, for example a SMS or SMMS material, comprising aspunbonded, a melt-blown and a further spunbonded layer or alternativelya carded chemical-bonded nonwoven. The non-woven material may inparticular be latex bonded. Exemplary upper acquisition layers 52 aredisclosed in U.S. Pat. No. 7,786,341. Carded, resin-bonded nonwovens maybe used, in particular where the fibers used are solid round or roundand hollow PET staple fibers (50/50 or 40/60 mix of 6 denier and 9denier fibers). An exemplary binder is a butadiene/styrene latex.Nonwovens have the advantage that they can be manufactured outside theconverting line and stored and used as a roll of material.

Further useful nonwovens are described in U.S. Pat. No. 6,645,569(Cramer et al.), U.S. Pat. No. 6,863,933 (Cramer et al.), U.S. Pat. No.7,112,621 (Rohrbaugh et al.), US 2003/148684 (Cramer et al.) and US2005/008839 (Cramer et al.).

The acquisition layer 52 may be stabilized by a latex binder, forexample a styrene-butadiene latex binder (SB latex). Processes forobtaining such latices are known, for example, from EP 149880 (Kwok) andUS 2003/0105190 (Diehl et al.). In certain embodiments, the binder maybe present in the acquisition layer 52 in excess of about 12%, about 14%or about 16% by weight. SB latex is available under the trade nameGENFLO™ 3160 (OMNOVA Solutions Inc.; Akron, Ohio).

A further acquisition layer (not shown) may be used in addition to thefirst acquisition layer 52 described above. For example a tissue layermay be placed between the first acquisition layer 52 and thedistribution layer 54. The tissue may have enhanced capillaritydistribution properties compared to the acquisition layer 52 describedabove. The tissue and the first acquisition layer 52 may be of the samesize or may be of different size, for example the tissue layer mayextend further in the back of the absorbent article than the firstacquisition layer 52. An example of a hydrophilic tissue is a 13 to 15gsm high wet strength tissue made of cellulose fibers from supplierHavix.

Fastening System 42, 44

The absorbent article may include a fastening system. The fasteningsystem can be used to provide transversal tensions about thecircumference of the absorbent article to hold the absorbent article onthe wearer. This fastening system is not necessary for training pantarticle since the waist region of these articles is already bonded. Thefastening system usually comprises a fastener 42 such as tape tabs, hookand loop fastening components, interlocking fasteners such as tabs &slots, buckles, buttons, snaps, and/or hermaphroditic fasteningcomponents, although any other known fastening means are generallyacceptable. A landing zone 44 is normally provided on the front waistregion of the article for the fastener 42 to be releasably attached.Some exemplary surface fastening systems are disclosed in U.S. Pat. Nos.3,848,594, 4,662,875, 4,846,815, 4,894,060, 4,946,527, 5,151,092 and5,221,274 (Buell). An exemplary interlocking fastening system isdisclosed in U.S. Pat. No. 6,432,098. The fastening system may alsoprovide a means for holding the article in a disposal configuration asdisclosed in U.S. Pat. No. 4,963,140 (Robertson et al.)

The fastening system may also include primary and secondary fasteningsystems, as disclosed in U.S. Pat. No. 4,699,622 to reduce shifting ofoverlapped portions or to improve fit as disclosed in U.S. Pat. Nos.5,242,436, 5,499,978, 5,507,736, and 5,591,152.

Front and Back Ears 46, 40

The absorbent article may comprise front ears 46 and back ears 40 as isknown in the art. The ears can be integral part of the chassis, forexample formed from the topsheet and/or backsheet as side panel.Alternatively, as represented in FIG. 12, they may be separate elementsattached by gluing and/or heat embossing. The back ears 40 areadvantageously stretchable to facilitate the attachment of the tabs 42on the landing zone 44 and maintain the taped diapers in place aroundthe wearer's waist. The front ears 46 may also be elastic or extensibleto provide a more comfortable and contouring fit by initiallyconformably fitting the absorbent article to the wearer and sustainingthis fit throughout the time of wear well past when absorbent articlehas been loaded with exudates since the elasticized ears allow the sidesof the absorbent article to expand and contract.

Barrier Leg Cuffs 34 and Gasketing Cuffs 32

Absorbent articles such as diapers or training pants may typicallyfurther comprise components that improve the fit of the article aroundthe legs of the wearer, in particular barrier leg cuffs 34 and gasketingcuffs 32. The barrier leg cuffs 32 may be formed by a piece of material,typically a nonwoven, which is partially bonded to the rest of thearticle and can be partially raised away and thus stand up from theplane defined by the topsheet, when the article is worn by the user. Thebarrier leg cuffs 34 can provide improved containment of liquids andother body exudates approximately at the junction of the torso and legsof the wearer. The barrier leg cuffs 34 may extend at least partiallybetween the front edge and the back edge of the absorbent article onopposite sides of the longitudinal axis and may at least be presentadjacent to the crotch point (C).

The barrier leg cuffs 34 may be delimited by a proximal edge joined tothe rest of the article, typically the topsheet and/or the backsheet,and a free terminal edge intended to contact and form a seal with thewearer's skin. The barrier leg cuffs 34 may be joined at the proximaledge with the chassis of the article by a bond which may be made forexample by adhesive bonding, fusion bonding or combination of knownbonding means. The bond at the proximal edge may be continuous orintermittent.

The barrier leg cuffs 34 can be integral with (i.e. formed from) thetopsheet or the backsheet, or more typically be formed from a separatematerial joined to the rest of the article. Typically the material ofthe barrier leg cuffs may extend through the whole length of the articlebut is “tack bonded” to the topsheet towards the front edge and backedge of the article so that in these sections the barrier leg cuffmaterial remains flush with the topsheet. Each barrier leg cuff 34 maycomprise one, two or more elastic strings 35 close to this free terminaledge to provide a better seal.

In addition to the barrier leg cuffs 34, the article may comprisegasketing cuffs 32, which are formed in the same plane as the chassis ofabsorbent article, in particular may be at least partially enclosedbetween the topsheet and the backsheet, and may be placed transversallyoutwardly relative to the barrier leg cuffs 34. The gasketing cuffs 32can provide a better seal around the thighs of the wearer. Usually eachgasketing leg cuff 32 will comprise one or more elastic string orelastic element 33 comprised in the chassis of the diaper for examplebetween the topsheet and backsheet in the area of the leg openings.

U.S. Pat. No. 3,860,003 describes a disposable diaper which provides acontractible leg opening having a side flap and one or more elasticmembers to provide an elasticized leg cuff (a gasketing cuff). U.S. Pat.No. 4,808,178 (Aziz) and U.S. Pat. No. 4,909,803 (Aziz) describedisposable diapers having “stand-up” elasticized flaps (barrier legcuffs) which improve the containment of the leg regions. U.S. Pat. No.4,695,278 (Lawson) and U.S. Pat. No. 4,795,454 (Dragoo) describedisposable diapers having dual cuffs, including gasketing cuffs andbarrier leg cuffs. All or a portion of the barrier leg and/or gasketingcuffs may be treated with a lotion.

Elastic Waist Feature

The absorbent article may also comprise at least one elastic waistfeature (not represented) that helps to provide improved fit andcontainment. The elastic waist feature is generally intended toelastically expand and contract to dynamically fit the wearer's waist.The elastic waist feature preferably extends at least longitudinallyoutwardly from at least one waist edge of the absorbent core 28 andgenerally forms at least a portion of the back side of the absorbentarticle. Disposable diapers can be constructed so as to have two elasticwaist features, one positioned in the front waist region and onepositioned in the back waist region. The elastic waist feature may beconstructed in a number of different configurations including thosedescribed in U.S. Pat. Nos. 4,515,595, 4,710,189, 5,151,092 and5,221,274.

Relations Between the Layers and Components

Typically, adjacent layers will be joined together using conventionalbonding method such as adhesive coating via slot coating or spraying onthe whole or part of the surface of the layer, or thermo-bonding, orpressure bonding or combinations thereof. Most of the bonding betweencomponents is not represented in the Figures, for clarity andreadability. Bonding between the layers of the article should beconsidered to be present unless specifically excluded. Adhesives may betypically used to improve the adhesion of the different layers, forexample between the backsheet and the core wrap. The adhesives used maybe any standard hot-melt glue as known in the art.

If an acquisition layer 52 is present, it may be advantageous that thisacquisition layer is larger than or least as large as the distributionlayer 54 in the longitudinal and/or transversal dimension. Thus thedistribution layer 54 can be deposited on the acquisition layer 52. Thissimplifies handling, in particular if the acquisition layer is anonwoven which can be unrolled from a roll of stock material. Thedistribution layer may also be deposited directly on the absorbentcore's upper side of the core wrap or another layer of the article.Also, an acquisition layer 52 larger than the distribution layer allowsone to directly adhere the acquisition layer to the storage core (at thelarger areas). This can provide increased article integrity and betterliquid communication.

The absorbent core and in particular its absorbent material layer(s) mayadvantageously be at least as large and long and advantageously at leastpartially larger and/or longer than any of the layer in theacquisition-distribution system (“ADS”). This is because the absorbentmaterial in the absorbent core 28 can usually more effectively retainfluid and provide dryness benefits across a larger area than the ADS.The absorbent article may have rectangular absorbent material depositionarea 8 and a non-rectangular (shaped) ADS. The absorbent article mayalso have a rectangular (non-shaped) ADS and a rectangular layer ofabsorbent material 8.

Method of Making

The absorbent article of the invention may be made by any conventionalmethods known in the art. In particular the articles may be hand-made orindustrially produced at high speed on a modern converting line. Theabsorbent structure and absorbent core of the invention can inparticular by adapting the method generally disclosed for makingabsorbent layers disclosed in WO2008/155699 with some adaptations. Sucha method is schematically disclosed in FIG. 13.

A first printing unit 134 for making an absorbent structure inaccordance with the first aspect of this invention is illustrated on theleft side of FIG. 13. The first printing unit 134 comprise an auxiliaryglue applicator 148 for applying the auxiliary glue 72 to the substrate16, a first rotatable support roll 152 for receiving the first substrate16, a first hopper 154 for holding and dispensing the absorbentparticulate polymer material, a first printing roll 156 for depositingthe absorbent particulate polymer material land areas 75 from the hopper154 to a deposition area 73 on the substrate 16, and a firstthermoplastic adhesive material applicator 158 for applying the fibrousthermoplastic adhesive material 74. The auxiliary glue applicator 148may be a nozzle system which can provide a relatively thin but widecurtain of thermoplastic adhesive material as suggested inWO2008/155699, but may also alternatively and advantageously comprise aslot coater for applying simultaneously several slots of auxiliary glue72 longitudinally along the width of the substrate. The auxiliary glueapplicator may be fitted with a manifold which intermittently stops thedelivery of the auxiliary glue so that there the auxiliary layer is notapplied or applied at a reduced amount in the area of the substratecorresponding to the zones of lower absorbent material amount. The SAPprinting roll 156 and fibrous layer adhesive applicator 158 may be asfurther detailed in WO2008/155699.

The absorbent structure 70 obtained by the printing unit 134 may bedirectly put in face to face relation with a second substrate 16′, ormay be combined with a second absorbent structure 70′, to form anabsorbent core. This second absorbent structure 70′ may then be formedon the second printing unit 132 as shown on the right side of FIG. 13,which may be generally identical to the first printing unit 134. Thesecond printing unit 132 may comprise a second auxiliary glue applicator136 which may be a slot coater for applying an auxiliary glue to thesubstrate 16′, a second rotatable support roll 140 for receiving thesubstrate 16′, a second hopper 142 for holding absorbent particulatepolymer material, a second printing roll 144 for transferring theabsorbent particulate polymer material to the substrate 16′, and athermoplastic adhesive material applicator 146 for applying thethermoplastic fibrous adhesive material 74′ to the substrate 16′ and theabsorbent particulate polymer land areas 75′ thereon.

The absorbent structures may for example be combined by applyingpressure in the nip between the two support rolls 140, 152. Thelongitudinal side seals 284, 286 may be formed for example as a C-wrapin the seal forming guide roller 160. The absorbent cores 28 can then beindividualized by forming the front and back end seals and cutting theweb of the core material at the required interval. The continuous flowof absorbent cores can then be integrated into a converting process formaking an absorbent article.

Test Procedures

The values indicated herein are measured according to the methodsindicated herein below, unless specified otherwise. All measurements areperformed at 21° C.±2° C. and 50%±20% RH, unless specified otherwise.All samples should be kept at least 24 hours in these conditions toequilibrate before conducting the tests, unless indicated otherwise. Allmeasurements should be reproduced, if available, on at least 4 samplesand the average value obtained indicated, unless otherwise indicated.

Centrifuge Retention Capacity (CRC)

The CRC measures the liquid absorbed by the superabsorbent polymerparticles for free swelling in excess liquid. The CRC is measuredaccording to EDANA method WSP 241.2-05.

Dry Absorbent Core Caliper Test

This test may be used to measure the caliper of the absorbent core(before use i.e. without fluid loading) in a standardized manner.

Equipment: Mitutoyo manual caliper gauge with a resolution of 0.01 mm,or equivalent instrument.

Contact Foot: Flat circular foot with a diameter of 17.0 mm (±0.2 mm). Acircular weight may be applied to the foot (e.g., a weight with a slotto facilitate application around the instrument shaft) to achieve thetarget weight. The total weight of foot and added weight (includingshaft) is selected to provide 2.07 kPa (0.30 psi) of pressure to thesample.

The caliper gauge is mounted with the lower surface of the contact footin an horizontal plane so that the lower surface of the contact footcontacts the center of the flat horizontal upper surface of a base plateapproximately 20×25 cm. The gauge is set to read zero with the contactfoot resting on the base plate.

Ruler: Calibrated metal ruler graduated in mm.

Stopwatch: Accuracy 1 second.

Sample preparation: The core is conditioned at least 24 hours asindicated above.

Measurement procedure: The core is laid flat with the top side, i.e. theside intended to be placed towards the wearer in the finished articlefacing up. The point of measurement (e.g. the crotch point C) iscarefully drawn on the top side of the core taking care not to compressor deform the core.

The contact foot of the caliper gauge is raised and the core is placedflat on the base plate of the caliper gauge with the top side of thecore up so that when lowered, the center of the foot is on the markedmeasuring point.

The foot is gently lowered onto the article and released (ensurecalibration to “0” prior to the start of the measurement). The calipervalue is read to the nearest 0.01 mm, 10 seconds after the foot isreleased.

The procedure is repeated for each measuring point. If there is a foldat the measuring point, the measurement is done in the closest area tothis point but without any folds. Ten articles are measured in thismanner for a given product and the average caliper is calculated andreported with an accuracy of one tenth mm.

Absorbent Article Caliper Test

The Absorbent Article Caliper Test can be performed as for the DryAbsorbent Core Caliper Test with the difference that the caliper of thefinished absorbent article is measured instead of the caliper of thecore. The point of measurement may be the intersection of thelongitudinal axis 80 and transversal axis 90 of the absorbent article,or any other points of the article. If the absorbent articles areprovided folded and/or in a package, the articles to be measured areunfolded and/or removed from the center area of the package. If thepackage contains more than 4 articles, the outer most two articles oneach side of the package are not used in the testing. If the packagecontains more than 4 but fewer than 14 articles, then more than onepackage of articles is required to complete the testing. If the packagecontains 14 or more articles, then only one package of articles isrequired to perform the testing. If the package contains 4 or fewerarticles then all articles in the package are measured and multiplepackages are required to perform the measurement. Caliper readingsshould be taken 24±1 hours after the article is removed from thepackage, unfolded and conditioned. Physical manipulation of productshould be minimal and restricted only to necessary sample preparation.

Any elastic components of the article that prevent the article frombeing laid flat under the caliper foot are cut or removed. These mayinclude leg cuffs or waistbands. Pant-type articles are opened or cutalong the side seams as necessary. Apply sufficient tension to flattenout any folds/wrinkles. Care is taken to avoid touching and/orcompressing the area of measurement.

EXAMPLE

An exemplary absorbent structure according to the first aspect of theinvention and roughly corresponding to the schematic view shown in FIG.1 can be made as follows. The substrate may be e.g. a 10 gsm SMSnonwoven substrate 390 mm long and 130 mm wide. The auxiliary glue (e.g.Fuller hot-melt adhesive 1286 or 1358) can be applied by slot coating ina pattern of 55 slots 1 mm wide with a distance of 1 mm between theslots over a width of about 110 mm. The slots can start at a distance of105 mm from the front edge of the substrate and extend up to a distanceof 140 mm from the back edge of the substrate for a total length 145 mm.The total amount of auxiliary glue on the substrate may be e.g. 0.080 g(80 mg). It is also alternatively possible to apply the auxiliary glueto a shorter width, for example 41 slots 1 mm wide with a separationdistance of 1 mm for a width of about 80 mm for the auxiliary glueapplication area. The application area may be centered on thelongitudinal centerline of the substrate.

A superabsorbent polymer in particulate form can be applied on thesubstrate in rectangular land areas oriented in the transversaldirection (x) of the substrate as shown on FIG. 1, each area being about10 mm wide and 110 mm long. The first land area may start at a distanceof 15 mm from the front edge of the substrate. The junction area thatseparates each land area may be about 1-2 mm long. The last land areamay be placed at a distance of 15 mm from the back edge of thesubstrate, thus providing the substrate with about thirty SAP landareas. The amount of SAP in each land areas may vary so as to providezones of lower amount and zones of higher amount of absorbent material.The SAP deposition area is notionally divided in 8 zones as illustratedin FIGS. 1 and 2 each zone being in this example 45 mm long andcomprising about four SAP land areas. The total amount of SAP in thestructure was about 6.75 g, thus an average amount of SAP of 0.844 g(6.75/8) per zone across the whole SAP deposition area. The distributionof SAP for each zone may thus be as follows:

Z1 Z2 Z3 Z4 Z5 Z6 Z7 Z8 Amount 0.87 0.97 1.18 1.26 1.05 0.71 0.42 0.29of SAP (g) Relative +3.1 +14.9 +39.8 +49.3 +24.4 −15.9 −50.2 −65.6difference (%)

The relative difference in percent is the actual amount of SAP in thezone minus the average amount in the 8 zones, this being divided by theaverage amount and multiplied by 100 (in thisexample=(x−0.844)/0.844*100), where x is the amount of SAP in the zoneconsidered and 0.844 g the average amount.

Zone 7 and zone 8 have amount of absorbent material which are at least20% by weight lower than the average amount (minus 50.2% and minus 65.6%respectively) and are thus zones of lower amount of absorbent materialas defined herein. Zones 3, 4 and 5 are zones of higher amount ofabsorbent material, having more than 20% by weight of absorbent materialrelative to the average amount.

The total amount of auxiliary glue in the structure may be 80 mg thus anarithmetic average of 10 mg (80/8) for each zone. The actual repartitionin the zones may be as follows, with relative differences beingcalculated by taking the actual amount minus the average amount anddiving the result by the average amount (=(y−10)/10*100), where y is theactual amount:

Z1 Z2 Z3 Z4 Z5 Z6 Z7 Z8 Amount 0 0 24.8 24.8 24.8 5.5 0 0 of auxiliaryglue (mg) Relative Absent Absent 148% 148% 148% −45% Absent Absentdiffer- ence (%)

The auxiliary glue application area is present in absorbent materialdeposition zones 3, 4, 5 and 6 and absent in zones 1, 2, 7 and 8. ZoneZ6 comprises a relatively low amount of auxiliary glue compared to thezones Z3, Z4, Z5. In this example the zones of lower amount of absorbentmaterial (Z7, Z8) do not have auxiliary glue applied thereon, while thezones of higher absorbent material amount have auxiliary glue applied(Z3, Z4, Z5) thereon. As an alternative, it is also possible to alsoapply the auxiliary glue in the first two zones Z1 and Z2 and also inthe rest of Z6 in addition to zones Z3-Z6 as described above, as thesezones Z1 and Z2, while not zones of higher amount of SAP, are not zonesof lower amount of SAP. Keeping a total amount of 80 mg auxiliary gluefor the whole of the absorbent structure, the repartition of theauxiliary glue in the zones is as follow:

Z1 Z2 Z3 Z4 Z5 Z6 Z7 Z8 Amount of 13.3 13.3 13.3 13.3 13.3 13.3 0 0auxiliary glue (mg) Relative +33% +33% +33% +33% +33% +33% Absent Absentdifference (%)

In this alternative, only zones Z7 and Z8 have no auxiliary glue.

In general, a fibrous thermoplastic layer (e.g. NW1151ZP hot-meltadhesive ex Fuller) may be uniformly sprayed at a basis weight of 5 gsmto cover the whole of the absorbent material deposition area, stoppingfor example at 5 mm from each transversal sides of the substrate (asillustrated in FIG. 1) to form an absorbent structure according to theinvention.

The absorbent structure described above can be combined with a secondabsorbent structure having generally the same repartition of land areasand junction areas and adhesive application. The land areas of the eachrespective substrate may be combined with an offset of e.g. ca. 5 mm inthe longitudinal direction so that land areas of one structure arecentered on the junction areas of the other structure. This allowsforming a combined substantially continuous absorbent material area. Thesecond substrate may be wider (e.g. 165 mm) than the first substrate, sothat transversally extending side flaps from the second substrate can beformed and folded around the longitudinal edges of the core and theexternal surface of the first substrate to form a C-wrap on thelongitudinal sides of the core, with one or several thin line ofadhesive applied longitudinally on the flaps to secure the seal. Thetransversal front and back ends of both substrates may be glued in faceto face relation to form two transversal seals.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

Every document cited herein, including any cross referenced or relatedpatent or application and any patent application or patent to which thisapplication claims priority or benefit thereof, is hereby incorporatedherein by reference in its entirety unless expressly excluded orotherwise limited. The citation of any document is not an admission thatit is prior art with respect to any invention disclosed or claimedherein or that it alone, or in any combination with any other referenceor references, teaches, suggests or discloses any such invention.Further, to the extent that any meaning or definition of a term in thisdocument conflicts with any meaning or definition of the same term in adocument incorporated by reference, the meaning or definition assignedto that term in this document shall govern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. An absorbent structure comprising: asubstantially planar substrate extending in a transversal direction anda longitudinal direction, an auxiliary glue applied directly over thesubstrate on an auxiliary glue application area, an absorbent materialdisposed in an absorbent material deposition area, wherein the absorbentmaterial deposition area can be notionally divided into eight depositionzones of equal length along the longitudinal direction; and wherein anamount of the absorbent material is profiled along the longitudinaldirection of the structure so that at least one of the eight depositionzones is a zone of lower absorbent material amount having an amount ofabsorbent material that is at least 20% by weight lower than the averageamount of absorbent material in the eight deposition zones, and theauxiliary glue is absent, or present at a level of at least 50% byweight lower than the average amount of auxiliary glue in the eightdeposition zones, in at least one of these zones of lower absorbentmaterial amount.
 2. The absorbent structure of claim 1, wherein at leastone of the eight deposition zones is a zone of higher absorbent materialamount having an amount of absorbent material that is at least 20%higher than the average amount of absorbent material in the eightdeposition zones and the auxiliary glue is present in at least one ofthese zones of higher absorbent material amount.
 3. The absorbentstructure of claim 1, wherein at least one zone of lower absorbentmaterial amount is situated in the back third of the structure, asmeasured in the longitudinal direction.
 4. The absorbent structure ofclaim 1, wherein the auxiliary glue is applied as a plurality oflongitudinally-extending slots.
 5. The absorbent structure of claim 4,wherein the plurality of longitudinally-extending slots have atransversal spacing there between of from about 0.5 mm to about 4 mm. 6.The absorbent structure of claim 5, wherein the slots have a width offrom about 0.5 mm to about 3 mm.
 7. The absorbent structure of claim 1,wherein the auxiliary glue application area has a surface which is nogreater than about 80% the surface of the absorbent material depositionarea.
 8. The absorbent structure of claim 7, wherein the auxiliary glueapplication area has a surface which is no greater than about 70% of thesurface of the absorbent material deposition area.
 9. The absorbentstructure of claim 1, wherein the auxiliary glue application area has asurface which is at least about 20% of the surface of the absorbentmaterial deposition area.
 10. An absorbent core comprising a firstabsorbent structure comprising a substantially planar substrateextending in a transversal direction and a longitudinal direction, anauxiliary glue applied directly over the substrate on an auxiliary glueapplication area, an absorbent material disposed in an absorbentmaterial deposition area, wherein the absorbent material deposition areacan be notionally divided into a plurality of deposition zones of equallength along the longitudinal direction; and wherein an amount of theabsorbent material is profiled along the longitudinal direction of thestructure so that at least ⅛^(th) of deposition zones comprises a lowerabsorbent material amount having an amount of absorbent material that isat least 20% by weight lower than the average amount of absorbentmaterial in the plurality of deposition zones, and the auxiliary glue isabsent, or present at a level of at least 50% by weight lower than theaverage amount of auxiliary glue in the plurality of deposition zones,in the at least ⅛th of deposition zones of lower absorbent materialamount, and a second substrate joined with the substrate of the firstabsorbent structure so that both substrates form a core wrap enclosingthe absorbent material of the absorbent core.
 11. The absorbent core ofclaim 10, wherein the absorbent material is immobilized on thesubstantially planar substrate.
 12. The absorbent core of claim 10further comprising a second absorbent structure, the second absorbentstructure comprising: the second substrate, a second absorbent material,wherein the first absorbent structure and the second absorbent structureare joined so that the first substrate and the second substrate formtogether a core wrap enclosing the first and second absorbent materials.13. The absorbent core of claim 10, wherein the first substrate and thesecond substrate are sealed at the periphery of the core by at least onetransversal end seal and/or at least one longitudinal side seal.
 14. Theabsorbent core of claim 10, wherein at least one of the substrates is anonwoven layer.
 15. The absorbent core of claim 14, wherein thesubstrate comprises spunbond and meltblown component layers such as aSMS or SMMS nonwoven layer.
 16. An absorbent article for personalhygiene, the article comprising: a liquid permeable topsheet; a liquidimpermeable backsheet; and the absorbent structure of claim 1 betweenthe topsheet and the backsheet.
 17. An absorbent article comprising atopsheet, backsheet and the absorbent core of claim 10.